Immediately after you implement the VirtualPathProvider proxy from my previous post you will notice a one fairly serious lack in it. Namely all the files within that provider will be hiding behind the registration form. That is not cool for a couple of reasons…

You may want to keep all of the files in one store – being forced to put them into a designated folder is not desired.

You may want to make some file freely available for some time and lock it after a while, or the other way around (e.g. to allow the robots to crawl it initially). having to move them is just silly and defeats the purpose.

So how do you discriminate the files that you want locked from those that you want to be publically available, and potentially from those that you want only the logged in users to be able to get?

Specifying the EPiServer File Metadata sweetness

One of the potential solutions would be to define a special rights group and check for that group for the people that have your “registered” magic-cookie. That however introduces a bogus group, and I would rather like to avoid that. However if you look into the FileSummary.config file that’s located in your web application folder you will find a slightly mysterious content. A bit of hacking reveals that you can actually add your own metadata to the file. For example adding the access rights based on what I’ve established above would look as follows (the content you can already find in the file that comes with the public templates that-we-all-oh-so-love is skipped):

Once you’ll update the framework to the extended one, you will immediately notice that… nothing has changed. Hmm… did something go wrong?

Well, not really. By default the framework will be run in the “legacy mode”. Thanks to an old article by our own Marek Blotny, I’ve learned how to build Plugin settings which are just perfect for the purpose!

So to configure and enable the new features you need to open your admin UI and in the “Config” click on the “Plugin Manager” item and select our framework plugin as shown in the picture

Back in the day when we started designing our last project we’ve been presented with a following problem – a big number of templates with slightly different sidebars.

Hmm…

Is sidebar a part of content? No, rather not. We don’t want the editors to have to setup the sidebar for every article they write (and the site has a few dozens of articles created on it every day).

Is sidebar more of a template thing? Well… more like it, but still… we have articles all over the site with different sidebar elements when the articles are in different parts of the site (ok so we could add rules what controls display in which part of the site). But wait! There’s more! The sidebar will be different for every language (region). Now we’re talking a dozen of templates or a rules engine just to make the sidebar different. Customising the template with properties isn’t ideal either as it makes EPiServer UI very cluttered. Additionally we want to change sidebars across many templates so the whole branch/section of the site will be able to share the same sidebar.

To a degree this is an academic discussion as we’ve been through it with the previous version of the site and we already knew that integrating this stuff into templates just won’t work and we will be in a world of pain just changing the templates over and over adding little tweaks and changes while the customer ads promotions and performs ad campaigns. Well, we can do it, of course, but it’s not a work a programmer will enjoy, and we all want to do new and more exciting things, don’t we?

We have an internally developed module to make something like that, that is fully home-grown by another internal team (we now have 3 “squads” capable or making incredible things with EPiServer and we tend to share a lot of technologies and try to rotate people around to adopt the good habits and experiences) and I was (and still am) VERY impressed by it. The technology uses EPiServer pages for defining every module (which are located somewhere outside the site root branch. and then you can mix and match them either declaratively in the code) or by handpicking them in the UI. It’s really cool, though, during the discussions it turned out that we might have to add big chunks of functionality and might end up with separate branches of module-pages for different languages/regions, but… frankly… about that time an article by Ted Nyberg reminded me about a technology I have read about quite a while ago in an article by Stein-Viggo Grenersen and ooohhhhhh… I got seduced. I really wanted to try if for a long time and Ted’s article made it a snap to try and get convinced, and more important… convince Stu ;) that it’s the right way to explore.

shownInFileManager is “false” as there is nothing to present for the user in the file manager.

allowedReferrers is the regular expression containing the filter for sites that are allowed to access the path provider and get images. This has been added so that your server does not turn into the internet’s text-image open service :)

allowNullReferrer should be set to false in production environment but allows for testing by directly creating URL’s without using a page to fill in the referrer.

replacementStrings – this one actually turned out to be very useful since some characters are invalid and not even reaching the VPP if EPiServer or ASP detects them. so to allow for characters like colon or < or even a dot (which would make it hard to form regular expression if it was explicitly available) or * you need to create an escape token for them. The string is a coma separated list of token,value,token,value,…

virtualPath is something you need to change if you want your VPP to serve images under a different root level folder. (e.g. if you have a page with that name already)

Additionally for IIS6 (most common scenario) you need to add <location> node to configuration for the VPP to work.

The module code is already available on Epicode SVN, the relevant wiki pages will be following as soon as documentation is complete.

The use case is as follows:

The client wants the site to look exactly as in a template provided as a image,

the text is using a non standard font that is not available on 60% of Windows machines,

the site does not use flash.

the site needs to be equally good looking in IE6 (more about it later)

The solution was to generate images, but how to do it the right way? This has presented us with a once-in-a-lifetime :) opportunity to create a virtual path provider, do something good and learn something new & cool in the process.

Creating a new virtual path provider.

this functionality in itself is fairly well documented on MSDN one thing to pay attention to is to remember to pass the control to the next provider in the provider queue if your provider does not want to serve the request, so in my case:

this is necessary so you don’t have to have all-or nothing solution (your provider either serving everything the user requests or not being accessible at all) and honestly I’ve spent quite a while before I found out that… I was just being silly – thinking the technology by itself will resolve that ;)

If your Virtual path provider does not actually implement directories you don’t have to make the very provider to do a lot of complicated things. you are perfectly fine to limit the implementation to providing a custom constructor so that EPiServer passes you the configuration data and a couple of methods to tell whether a file is what you want to handle or not

// this one is actually really cool - whatever values you set in your web.config // will be passed to you in the collection so you can really make your VPP

// This one resolves if the file can be generatedpublicoverridebool FileExists(string virtualPath) { /* ... */ }
// Pretty much only passes the info that directory was not found // found if the virtual path matches a path that we should handlepublicoverridebool DirectoryExists(string virtualDir) { /* ... */ }
// Retrieves the virtual file that generates the image if the// Virtual path matches our pattern or disregards the request if it doesn'tpublicoverrideVirtualFile GetFile(string virtualPath) { /* ... */ }
// Again this is only a pass through method as we don't support directoriespublicoverrideVirtualDirectory GetDirectory(string virtualDir) { /* ... */ }

Now that we have ASP passing the request to us we need to wonder how to format the request in a way that is intuitive to the user, I wanted the URL to be straightforward and follow the path of EPiServer’s friendly URL-S so that they are easily formed by editors. So how about:

Ok.. well…, that won’t fly for GIFs – the font will be plain ugly if I don’t use antialiasing and if I do I will have an ugly black background underneath it. The solution to that would be using translucent PNG (which the VPP supports) but IE6 does not support those with transparency without ugly hacks. So I need to replace the blacks with a hint so that it generates a background colour when it merges the background with the font for antialiasing. For the sake of this article let’s assume it was an easy switch (IT WASN’T!) and let’s extend the URL to:

For the curious

The final string format matching regular expression looks as follows:

Regex regex = newRegex(
@"^(?<colour> # The first match - starting form the beginning of the string

([0-9a-fA-F]{3}|[0-9a-fA-F]{6}|[a-zA-Z]*)) # match either a 6 hex digit string or a name of a known color - this is for text color / # now we expect the first separating slash (?<hint> # next match group is about background hint for antialiasing ([0-9a-fA-F]{3}|[0-9a-fA-F]{6}|[a-zA-Z]*)) # match either a 3 or 6 hex digit string or a name of a known color - this is for antialiasing color hint / # again separating slash (?<font>[\w\s]*) # font family name - accept white spaces / # yet another separating slash (?<size>[\d]{0,3}) # font size / # oh noes! another slash! ((?<style>[BIUSRN\s]*) # font style Bold, Italic, Underline, Strikethrough /){0,1} # this group is optional. ((?<transform>[\w]*) # transformation name as specified with System.Drawing.RotateFlipType - this group is optional /){0,1} # this group is optional too. (?<text>[\s\S]*[^\.]) # the text to render - basically anything but a dot - use relacement strings for dots [\.] # separating dot - now that's a nice change! (?<extension>(png|gif)) # the file extension - so that we know whether to generate png or gif $ # everything comes to an end ",
RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.IgnorePatternWhitespace | RegexOptions.CultureInvariant);

Usability concerns

The Colours can be provided as both named Colours (red, green, etc..) or html hex formatted colours (e.g. ff00bb, fob, fff, badfoo) both 6 and 3 hex digits strings are accepted.

The URL accepts spaces, and whatever text string that cannot be passed as a part of the url or is invalidated by EPiServer can be escaped by defining a token for it in web.config so for example as you can see in the above url the end of line “\n” character has been escaped into $eol$.

Obviously the font selection is limited to what is installed on your server.

Performance concerns

The basic concern that comes to mind is – how does this impact the server performance if the image is generated every time? Even though the performance impact seemed to be negligible I’ve decided to cache content. These things simply pile up if you have a high load site so why take the chance? Once an URL is called it is saved on first generation asserting the uniqueness of each parameter. Colours like black and 000 will be treated as same colour and cached only once.

Security concerns

So what was done to prevent our server to be an open server for generating images for everyone on the Internet? The VPP only allows for the images to be generated if the request referrer is in a domain or a host that is specified in the web.config. Additionally for testing you can enable the referrer to be null (direct call to images, as opposed to referring to them from a page).

Also as a seconds line of defence, it’s wise to define the cache folder on a share with a quota so we don’t get our server filled up with images should the referrer limiting measure fail for some reason.

We’ve not been talking much about it and that’s partially my fault as well (busy with other projects), but Cognifide has a really cool initiative called Cognifide Labs that we intend to grow over time. The plan is to devote up to 10% company time into side projects that help us grow expertise and allow our devs to dwell into interesting technologies, methodologies and languages and develop their skills.

One of the first projects (that I took part in) is CogniScale – an app that allows FlexiScale users to manage their servers. Here’s the story…

Being the agile company taking part in many EPiServer projects we never seem to have enough environments to test our web-apps and software in general in various scenarios. We find ourselves constantly reinstalling and trying to keep our servers in a state that can can at least remotely be called as stable. After all how many deployments and tearing down of various EPiServer, CruiseControl, TeamCity, SQL Server and other "I need to have" apps can a server take before slowing down to a crawl or collapsing all together (that said I bow before our faithful THOTH for taking all the abuse it does). We definitely needed more servers! And we needed them now!

Early this year we’ve started to talk to the guys at XCalibre that came up with a great idea. What if you could have an unlimited amount of servers available for you at any given time? I mean really what if you could have 0 servers one day and the next day have a rich farm of servers for literally no cost, paying only when you power them up and not paying a bit if you take them down. This turned out to be quite a project for them that turned to materialize as FlexiScale. (you can read more about it here). Looking at all that I’ve mentioned before while eliminating the cost of maintaining the servers locally we decided to give FlexiScale a spin.

Thereseems to be a storm over at over at the Internet about Microsoft going Cross platform and “opening the common language runtime to a multitude of platforms”. What seems to be a false perception that even such respectable podcasts as Buzz Out Loud or even TWIT fail to realize and mislead people on is that this has NOTHING to do with portable .Net desktop applications. Someone even suggested at one of the BOL podcasts that it’s Microsoft’s attempt to put .Net Framework on Linux servers. (Huh? Beg your pardon?) You may have not noticed it but when they say about cross-platform capability of Silverlight it always says Windows, Mac.. and then on a single breath they start enumerating browsers. A casual listener just measures the quantity and the list has an impressive 5-6 bullets. heh… wait… erm… not really… it’s actually only 2 platforms. You cannot enumerate browsers as platforms! You share 99% implementation between them, the only cross-browser thing is the interaction between the plugin and the host browser!

As a .Net developer this pretty much makes me laugh through tears. What an excellent publicity stunt. First of all, Microsoft does not plan to release a Linux version. It’s cross-platformedness (is that a word?) refers strictly to the fact that there has been a runtime engine port made for a Mac. What was ported? The CLR and the DLR. Big deal! This has been there in a form of Mono years ago! And the CLR is available for Linux for a few years now. How is that suddenly an exciting thing?

If you’re interested in what exactly was done you may want to look at the interview with Scott Guthrie, GM of the Silverlight team. GAC was not ported. Wait! GAC WAS NOT PORTED?! Only a subset of classes that are needed inside a browser. Basic GC, no ASP.Net. It’s nothing like a cross platform version of a full .Net framework. this is also nothing really that new from the cross platform point of view – this kind of stunt was already pulled by Microsoft in form of the Compact version of the .Net framework. Something similar has already been done in terms of XNA – which is a form of .Net framework for XBox. In fact Silverlight is much more like XNA than it is like the full .Net framework.

Second of all the only open part is the DLR which is actually developed in an “embrace and devour” fashion. Ruby, Python and the likes developers – we love you! come join us under our Common Language runtime! Of course Microsoft will open it. Those developers are all about open and free this makes a lot of sense doing it this way. Give something, get a lot in return. Don’t get me wrong, I love the dynamic extensions, and I really like what’s being developed in the DLR, but make no mistake, the motives haven’t changed.

In the end CLR has been open for a long time and it’s not where the most exciting part of the development is. It’s the framework. I’ve not seen a word about Windows forms being ported. Or any of the ASP.Net namespaces on that mater. Heck even Mono has big ASP.Net 1.0 and chunks of 2.0. If you look at the image where do you see the CLR?

It’s the small middle circle inside the big one. That’s a far cry from releasing .Net as a standalone portable framework. And if you think about it, it does not make any sense from Microsoft’s point of view to go the whole way. What for? for it to make Windows expendable? Ridiculous!

My feeling is that (other than making another bucket of money), partially the motives behind is is to kick Adobe’s butt. If it did not occur to you yet, Microsoft and Adobe are full-out at war at this point. PDF is combated with XML Digital Paper, Flash has its Silverlight, Shockwave (& Macromedia Director) has Blend and XAML now and so on…

While Adobe made PDF readily-available to other software companies such as Apple, Sun, Corel, and OpenOffice, when it came to deep-pocketed Microsoft, Adobe took a different stance, demanding that it remove the feature and charge a separate fee.

In response, Microsoft agreed to remove the feature, but refused to charge consumers separately for it. Adobe consequently sought negotiating leverage by threatening to sue before the EC, despite the fact that neither Adobe nor Microsoft are based in Europe, neither operates major production facilities there, and neither maintains primary business locations there.

Now that we have a few myths busted, I don’t want you to think that I am not excited by Silverlight.

The coolness ensues

It is still incredibly cool that they are doing it and not for the cross platform reasons (although it’s nice), and not for the multi browser compatibility (even nicer), but for it’s roots in the full framework. For us .Net developers it’s like one day we woke up and we knew how to write Action Script (Flash) applications. The Silverlight download is only 5 meg, so in the broadband world it’s going to be on almost every computer fairly quick. We will have a robust development environment for developing those applets in less than a year. It’s root in the .Net framework roots will make it talk seamlessly to our IIS embedded apps and services. You wanted web applications?

You asked for web applications? We will deliver… … only they will be desktop applications running inside a browser we approve....… and on any platform we choose for you…… the best of both worlds – no matter if you want to run them in Windows OR in Internet Explorer. :)

But honestly – should you use some artificial and clunky surrogates of instantly-responsive-interactivity in forms of AJAX when you can have the real thing running faster and delivering much wider functionality? Developing a browser apps was possible before, but .Net was never perceived as a platform specifically designed for that kind of activity, the quasi multi-platform/browser compatibility has a chance to change that perception. Perfect crime :)

I think we’re mostly finished investigating ObjectStore for now. In this article I’ll try to finish up on the apsects of using the Object store in a real life solution that is a basic Page comments. In my previous article concerning ObjectStore I have described a way of storing and retrieving an object from the Store, which is fine and dandy if we know exactly the object’s OD, for example if we reference it from a page. But what good is a store like that if we cannot search it for content? The problem we were trying to solve using ObjectStore was storing comments for ANY Episerver page without having to do anything to the page type. We might need that for the upcoming project so the discovery may prove useful since this is a really neat way of storing objects.

So the class that we are going to store needs to persists the following values:

You might have noticed that contrary to what I did before this class has some of its fields tagged with [Indexed(true)] attribute. This is required by the store object if we ever want to query the store for the class using those fields as a filtering criteria. The page also implements the required IItem interface (although the properties required by the interface are not shown in the excerpt) as well as our internal IPageComment which is added there for the purpose of easy switching of implementations. We intend to implement it on both ObjectStore and using NHibernate to make sure we get the best performance possible out of our solution. This interface is to allow us to easily switch between the 2 implementations.

Back to the ObjectStore

First we need to introduce a few new classes EPiServer uses for querying the Store. The namespace that scopes the querying consists of the following entities:

Really there is not much meat there. The interesting part comes in the object retrieval. Even though the Search namespace does not look like it offers much, you can still build a fairly fophisticated filter with it. following code retrieves comments for a specific PageLinkID. The comments can be filtered by date and since the call is used to retrieve the page for viewing, we probably only want the ones that are public (meaning they have not been removed by the comment moderator).

You nahe to agree, this really IS neat. All you need to do now to place the comments on a page is a few lines of code to bind the data from the Store with a repeated of a kind, and a set of edit boxes with a submit button :)

This is basically how much code the submission and retrieval the comments comment take:

Since IIS on XP seems to be handling only one site at a time and I have multiple installations of EpiServer for different purposes on my machine I needed a fast way of switching between them.

Sure I could go to the administration console and do it manually, but hey, why waste 30 seconds every time you do it when you can actually batch waste them in a chunk of half an hour to automate it.

so here’s my findings.

The adsutil.vbs is the script you want to get intalled on your system somewhere in the search path. %systemroot% will do.
You will find the script on your XP CD in the \i386 folder. Unpack with the following command:

Another great tool I use that’s actually built into windows is reg.exe. this tool actually allows you to modify registry from command line. this was actually my initial approach to changing the path. It didn’t succeed to actually change the IIS root – but still it did the modification to the registry (that IIS just merrily ignored).

The challenge – The site that we will be coding will have its pages tagged with episerver categories. Implement a control that will list all the pages tagged with a specific category.
The control aspx code seems looks pretty straightforward and is derivative of some other controls that are defined in the EPiServer sample site:

The wirst thing you will notice after looking at the code is that PageList is pretty much a standard ASP.NET reinvented and rehashed. GREAT! Sounds like we can use the Data binding, right? That’s also true:

privatevoid Page_Load(object sender, System.EventArgs e)

{

if (!IsPostBack)

{

PageList1.DataSource = CategoryPages;

DataBind();

}

}

Does the trick of binding the data to the repeater… uh… oh… sorry… I mean PageList.

Now comes the hard and non-obvious part.

How does one actually find the pages assigned to a category? Short of calling the database directly to query the tblCategorypage table that comes to mind at first, it looks like EPiServer has a really cool page finding module that allows for simple yet fairly effective discovery of pages conforming to some developer defined criteria. Those criteria are defined by means of forming any necessary number of instances of PropertyCriteria class provided as a PropertyCriteriaCollection to Global.EPDataFactory. The result is handed to us back as a PageDataCollection. The fetching of the pages looks like this:

For this to work though, one has to define some more stuff in the web admin part of the site. the usual task is to define the Page Template for the control. In this case when you define the Page Template make sure to put the “AggregatedCategory” property in that should be of type Category selection. This property defines what categories you want your control to aggregate, and you can provide one or more of those. the other property that is required for this very control is “CategoryContainer” of type Page. This is solely for the purpose of having a master page that you define as the “main page” for the chosen category selection. It serves as a clickable header in the control. Unnecessary maybe but one would have to define a caption for the control anyway so why not make it meaningful.

The usage of the said control is trivial. A sample usage on the default EPiServer site looks like this:

*)… couldn’t ressist with the title joke :) For those not in subject… It’s a reference to a silly commercial of one of the market chain (Biedronka) in Poland that advertises recently with “My first *something*… from Biedronka*

The article is based on the knowledge I’ve gathered and work I’ve performed for Cognifide. Cognifide is an official partner EPiServer and the real contributor of the the control.